Systems, methods, and devices for structural 3D printing. A machine frame with multiple articulated arm segments pivoting within planes substantially parallel to the plane of material deposition are controlled by a controller to move a printhead attached to a material line to convey a construction material to a deposit position for dispensation. The controller is configured to receive 3D printing information and convert it to positional coordinates of the printhead, and to cause movement of the articulated arm segments and support members to position the printhead, while using sensor feedback. Vertical movement of the printhead is facilitated through one or more mechanisms such as elevating the machine platform, elevating the articulating arm segments, and/or the incorporation of a mast on one or more of the arm segments.